The brother of a woman who died after a routine operation in a London hospital may make legal history if a request is granted for a third inquest into her death.

Carmel Bloom died at the age of 54 after a kidney stone operation at the Roding Hospital, then run by Bupa, in Ilford in 2002. She had been transferred to Whipps Cross Hospital, in Leytonstone, where she worked as a health controller, but died 10 days later.

A first inquest in 2003 found she died of natural causes. The family appealed against that verdict and the High Court granted a second inquest because of doubts over evidence. In the second inquest in 2005, the jury overturned the natural causes verdict and found that an absence of post-operative intubation, monitoring and ventilation contributed to her death.

Carmel's brother, 61-year-old Bernard Bloom, a former member of St John's Wood Liberal Synagogue, has spent almost nine years and £2 million trying to discover why his normally fit and healthy sister died.

In 2007, the General Medical Council found a number of failings by two doctors who treated Ms Bloom, but which did not amount to misconduct, and in the same year the police began an investigation into Ms Bloom's death.

Two years after the second inquest, Mr Bloom discovered a previously withheld transcript of the emergency 999 call made by staff at Roding Hospital.

During the call, Bridget Matthews, the night sister, said Ms Bloom had suffered from a "pulmonary oedema" – fluid in the lungs – despite claiming "It had not got to the stage where there was visible pulmonary oedema" during the 2005 inquest.

Mr Bloom believes that this new evidence requires a new inquest.

He said: "I'm fighting for justice for my sister. I have had to do all the investigating by myself. We can't do anything for Carmel now, but we can try to stop this from happening to other people."

During a debate in the House of Commons last month, Lee Scott, MP for Ms Bloom's constituency, Ilford North, said: "All the way along the line, the family, who have suffered great distress over a prolonged period of time, have said that they simply want to know what happened, and want closure.

"I have been trying to help to the best of my ability.

"We are awaiting a number of key developments: the Attorney-General's consent to apply to the High Court for a fresh inquest; the outcome of a Nursing and Midwifery Council action against the two Bupa nurses; a decision to call for a full police investigation into the death of Carmel Bloom; the GMC's decision to re-charge the two doctors involved; and the decision by the health service ombudsman regarding the London ambulance service's actions, and the part that it played.

"There are so many questions that need to be answered before the poor family can move on and have closure."

A spokeswoman from Bupa declined to comment.